This invention relates to a multi-cylinder internal-combustion engine having two cylinder groups, the engine being used to power a motor vehicle. More particularly, the invention relates to a control device which allows one group of cylinders to be switched off during certain phases of operation to provide greater fuel economy.
On the basis of German Patent Publication DE-OS No. 29 97 934, an internal-combustion engine of the type according to the present invention is known where in the warmed-up condition, the switching-on and switching-off of the second group of cylinders takes place essentially without jerking. However, in that application, the warming-up phase of the internal-combustion engine is not taken into account.
Furthermore, according to German Patent Publication DE-AS No. 11 09 947, a multi-cylinder internal-combustion engine is known where individual or all cylinder groups receive fuel, according to the torque requirement, and which runs with all cylinders in the warming-up phase of all operational ranges. This Publication does not contain any reference to the fact that the feeding of the fuel-air mixture to the individual cylinders of the individual cylinder groups differs as a function of the load on the internal-combustion engine.
According to the publication "Possibility of Saving Fuel by Switching Off Cylinders," Schellmann et al, 1st Int. Automotive Fuel Economy Research Conference, Oct. 31-Nov. 1, 1979, an internal-combustion engine is known having two cylinder groups, each cylinder group having one throttle valve assigned that is located in an intake pipe. The position of the throttle valve can be changed by the gas pedal via a cam plate, the cam plate interacting with control levers that are arranged on the throttle valve shafts so that they are fixed with respect to rotation.
On the basis of Japanese Pat. No. 557 913, a six-cylinder internal-combustion engine is known, whose cylinders 1 thru 3 are switched off at low load. The internal-combustion engine includes an electronic device which, in the case of low temperatures, is influenced via a signal transmitter.
In addition in U.S. Pat. No. 4,153,053, shows a system for switching off some cylinders of a multi-cylinder internal-combustion engine where the switching-off of the cylinders takes place at low load. However, all cylinders are active during the warming-up phase.
Finally, according to German Patent DE-PS No. 30 44 248, a multi-cylinder internal-combustion engine is known having two cylinder groups, of which, when the internal-combustion engine is warmed-up, one cylinder group is inactive over a predetermined part-load range. The other group of cylinders operates normally. When the internal-combustion engine is cold, a control lever of the throttle valve of the usually inactive group of cylinders interacts with a cam range of a cam plate in such a way that this cylinder group also receives the fuel-air mixture. As a result, the starting of a vehicle having this internal-combustion engine is improved. However, because of the cam plate kinematics for the switching-off operation, the feeding of the fuel-air mixture is sharply reduced at the end of the predetermined part-load range which causes a reduction of torque which may result in the dying of the internal-combustion engine.
It is therefore the objective of the present invention to provide an internal-combustion engine which can be installed into a motor vehicle so that during the starting process of this vehicle, as well as in the warming-up phase of the internal-combustion engine, a sufficient torque is always made available by having both cylinder groups operate. During other phases of operation one group of cylinders may be switched off to provide greater fuel economy.
According to the present invention, an internal-combustion engine is provided such that when the vehicle is moving, in either forward or reverse, during the warm-up phase of the internal-combustion engine, and if necessary, as a function of a manually operable transmitting means or switch, both cylinder groups are activated in such a way that good operational characteristics, i.e. sufficient torque and no dying of the internal-combustion engine, are ensured over a predetermined part-load range. This is achieved by means of the radial cam and an actuating device which interact via the relaying of two bent levers constructed as a transmission rod structure. The radial cam, because it is disk-shaped and narrow, is easy to manufacture and can be mounted simply on the cam plate. The vacuum box of the actuating device can advantageously be influenced by a magnetic valve which is fitted into a vacuum pipe connected with the intake pipe, the magnetic valve receiving signals from an existing injection control device.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, an embodiment in accordance with the present invention.